> but I suppose that they might promote self-hosting on some kind of instances rented from Azure.

Yeah, Microsoft wants to sell Azure compute. They also want to sell their upcoming surface ultra hardware with the Nvidia chip in it. They preached hard on "unmetered intelligence" at this year's BUILD conference, went hard on local AI, and Azure Foundry, Windows Foundry Local, etc.

Copilot, both GH and M365, are also made to be model agnostic. Microsoft sells enterprise services and software, they'd prefer (I'm assuming) to not be locked in and dependent on any 1 or 2 model providers and would prefer plenty of options and competition in that space because they can just easily offer a model agnostic harness, integrated with the rest of their stack.